# Physics307L F09:People/Long/Balmer

## Balmer Lab Summary

SJK Incomplete Feedback Notice
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My feedback is incomplete on this page for two reasons. First, the value of the feedback to the students is low, given that the course is over. Second, I'm running out of time to finish grading!

Under the guidance of Professor Gold's manual, my partner Tom and I calculated a value for the Rydberg constant R. First we measured the wavelengths of various spectral lines from a hydrogen gas tube and also a deuterium gas tube. I used this website to figure out what value of n to use for each of the wavelengths in the Rydberg formula. Using excel I averaged our recorded wavelengths from four different colored spectral lines, and then plugged them each into the Rydberg formula, I then averaged these values together and calculated the standard error of the mean. Primary notebook entry

## Results

From Hydrogen spectra, $R=1.09421\pm .01821\times 10^{-7} m^{-1}$

From Deuterium spectra, $R=1.09416\pm .01746\times 10^{-7} m^{-1}$

The accepted value from NIST is $R=1.09737\times 10^{-7} m^{-1}$

I was extremely pleased with these results, but like I said in my primary lab notebook, I was a little bit skeptical because they seemed almost too good to be true. Hopefully this is not the case!

SJK 17:35, 18 December 2009 (EST)
17:35, 18 December 2009 (EST)
I agree with you that it's amazing how much precision optical spectroscopy provides! A couple quick notes: far too many digits on your uncertainties (usually one significant digit, sometimes two), and you're comparing to the R_infinity value, which probably means your missed the point about H and D having different reduced masses of the electron and different Rydberg constants.